In '50/50,' Joseph Gordon-Levitt plays a 27-year-old cancer patient who undergoes chemotherapy, then surgery. How accurate is the film?

The Premise: Adam Lerner (Joseph Gordon-Levitt) is a 27-year-old with a happy life revolving around his artist girlfriend, Rachel (Bryce Dallas Howard), and goofy friend Kyle (Seth Rogen). Adam develops back pain and night sweats, and an MRI of the spine reveals a rare malignancy known as a "schwannoma," or "neurofibrosarcoma." His oncologist says the tumor is caused by a gene mutation on chromosome 17 and that it has invaded the lumbar spine, causing bony erosions. The doctor recommends trying to shrink the tumor with chemotherapy before attempting to remove it surgically. As Adam undergoes treatment, he cycles through feelings of denial, anger and alienation, and receives psychotherapy from a caring doctoral student, Katherine McKay (Anna Kendrick). He is abandoned by Rachel but supported emotionally by Kyle and his mother, Diane Lerner (Anjelica Huston), even as he finds them enraging. The chemo causes side effects such as hair loss, vomiting and headaches but doesn't shrink the tumor. Finally, Adam receives an operation to remove the tumor.

The medical questions: What is a malignant schwannoma/neurofibrosarcoma? Is it genetically determined and is it generally treated with chemotherapy before surgery? Is surgery generally successful once it has caused bone erosion and spread locally? Is Adam's psychological reaction convincingly portrayed? How helpful is supportive psychotherapy in cases of life-threatening cancer? Can it lead to a personal attachment, as the movie portrays — and is that ethical? And is it common for friends or relatives to abandon those supposedly close to them when they get sick?

The reality: A schwannoma is a tumor of the Schwann cells that surround nerves and protect them. These tumors are typically benign, says Dr. Andrew Parsa, professor of neurosurgery and principal investigator at the Brain Tumor Research Center at UC San Francisco. A neurofibrosarcoma is a malignant type of schwannoma. It is a very aggressive cancer, Parsa says.

Neurofibrosarcomas do have a genetic basis and can include an abnormality in chromosome 17, Parsa adds. Fifty percent of these tumors are associated with a familial condition known as neurofibromatosis, which causes tumors of nerve support cells (including Schwann cells). In the movie, Adam does not appear to have neurofibromatosis.

Cutting out the tumor after first shrinking it "is a viable strategy with large tumors," says Dr. Paul McCormick, professor of neurological surgery and director of the Spine Center at Columbia University Medical Center. McCormick adds that sarcomas in general tend not to respond well to chemo but that "long-term control with such strategies can occur — although I am reluctant to use the term 'cure.' "

Parsa says that the use of chemotherapy before surgery with this type of tumor is "experimental and unproven." He says that the bone erosion Adam experiences is not an ominous sign and that local spread can be controlled with aggressive surgery, as the movie dramatically shows.

Patients suddenly diagnosed with cancer can oscillate among emotions that may not be in sync with their thoughts, says Dr. James Fraiman, director of psychosocial services at the New York University Clinical Cancer Center. Denial and anger are early common emotions, and newly diagnosed cancer patients can feel alienated from friends or family, as the movie shows. Several patients have described feeling as if they are "on the other side of a window observing their former life or their friends' life," Fraiman says.

Supportive psychotherapy — having someone emotionally available and willing to accept the patient's feelings without mixing in their own needs — can be incredibly helpful to patients and families dealing with this kind of crisis, Fraiman says. The urge of a patient like Adam to protect his family and friends from worry or fear can enhance a patient's sense of isolation, as the movie also shows.

The intensity of feelings between a therapist and a patient sick with cancer can be quite complex and has to be managed with caution, Fraiman says. One of the major tasks of a trainee therapist is to learn appropriate professional boundaries and to not depend on the patient to fulfill emotional needs. "It is very tempting with very sick or dying patients to be drawn into their lives, but a social or romantic relationship such as the movie describes would not be considered ethical within the mental health sphere," he concludes.

Fraiman says he has only rarely seen a loved one walk out on a new cancer victim, the way the movie portrays. It is much more common for friends, family and loved ones to "become emotionally unavailable" even though they may remain quite loyal. "Some people can deal and some can't," Fraiman says, "and one doesn't always know who that will be ahead of time."

Siegel is an associate professor of medicine at New York University Langone Medical Center. His latest book is "The Inner Pulse: Unlocking the Secret Code of Sickness and Health."